A showdown is expected this week in the U.S. Senate over President Bush's controversial nomination for a judgeship on a federal appeals court. The battle over Judge Charles Pickering is seen by many as a preview of an even more intense political fight expected if President Bush has an opportunity to appoint someone to the U.S. Supreme Court.

Opposition Democrats intend to use their narrow control of the Senate to block Judge Pickering's appeals court nomination in the Senate Judiciary Committee. Democrats and liberal advocacy groups oppose his appointment because of his opposition to abortion and what they say is a questionable record on civil rights.

Nan Aron is president of the Alliance for Justice, a national coalition of civil rights and women's rights groups that actively lobbies Democrats on liberal causes. "His judicial opinions have showed an indifference, if not a hostility to the rights of minorities and women and we believe on this basis that he is simply not qualified to be a circuit court judge," Ms. Aron said.

The opposition to the Pickering nomination has frustrated President Bush, who says Democrats should at least allow a vote by the full Senate. "I believe that they are holding this man's nomination up for political purposes and it's not fair and it's not right," Mr. Bush said.

Senate Republicans are particularly upset with liberal advocacy groups that have sought to portray Judge Pickering as insensitive to civil rights issues, a charge the judge and his Republican defenders take issue with. "For them, the means justify the ends at whatever the cost, including the gross distortion of this fine man's record and character," said Senator Orrin Hatch of Utah, the top Republican on the Senate Judiciary Committee.

But many on both sides of the political spectrum see the Pickering fight as a preview of an even more intense battle should any one of the nine sitting Supreme Court Justices announce plans to retire later this year. "I'm concerned also that what we have here with Judge Pickering is a warm-up for a later confirmation battle on the Supreme Court," said Republican Senator Arlen Specter of Pennsylvania.

In fact, special interest groups on both the left and right of the political spectrum seem to be gearing up for just such a battle. "If this president nominates a candidate who is beholden to special interests and whose views are opposed to the progress that we in this country have made in the areas of civil and women's rights, we will work hard to defeat that nominee," Nan Aron said.

But if they do, they will have a fight on their hands. "I think there is no question that liberal groups are chomping at the bit to raise money over provoking a fight over whatever nominee President Bush puts up for any Supreme Court vacancy that occurs. In doing that, you can count on liberal interest groups being as shrill as possible and as vitriolic as possible in what they try and do to derail that nominee," said Chip Mellor, president of the Institute for Justice, a conservative group active on legal issues.

Even as the partisan battle lines are being drawn over Judge Pickering, some senators from both parties are concerned that the process of nominating and confirming federal judges has already become too politicized. "I fear we are inching toward a place where no one can be confirmed, that we call just can continue to get more dug in and more partisan and the wheels will grind to a halt," said Republican Senator Mitch McConnell of Kentucky.

At the moment there is no indication that any of the nine Supreme Court justices are planning to retire after the current court term ends in June. But with three of the justices at least 70 years old, court analysts say it is possible that a retirement could be announced in the not too distant future.